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Glossary of British ordnance terms AI simulator
(@Glossary of British ordnance terms_simulator)
Hub AI
Glossary of British ordnance terms AI simulator
(@Glossary of British ordnance terms_simulator)
Glossary of British ordnance terms
This article explains terms used for the British Armed Forces' ordnance (weapons) and ammunition. The terms may have different meanings depending on their usage in another country's military.
Between decks: applies to a naval gun mounting in which part of the rotating mass is below the deck, and part of it is above the deck. This allows for a lower profile for a turret, meaning that the turrets need not be superfiring (i.e. they can be mounted on the same deck and not obstruct each other at high angles of elevation).
The term BL, in its general sense, stood for breech loading, and contrasted with muzzle loading. The shell was loaded via the breech (i.e. the gunner's end of the barrel, which opened) followed by the propellant charge, and the breech mechanism was closed to seal the chamber.
Breech loading, in its formal British ordnance sense, served to identify the gun as the type of rifled breechloading gun for which the powder charge was loaded in a silk or cloth bag and the breech mechanism was responsible for "obturation" i.e. sealing the chamber to prevent escape of the propellant gases. The term BL was first used to refer to the Armstrong breechloaders, introduced in 1859. Following the discontinuation of Armstrong breechloaders and the period of British rifled muzzle-loaders RML, British breechloaders were re-introduced in 1880. At this point the term rifled breech-loaders RBL was retrospectively introduced to refer to the Armstrong breechloaders, which had a totally different breech mechanism, and since then the term breech-loaders BL has applied exclusively to the type of breechloader introduced from 1880 onwards, using an interrupted-screw breeches.
Early British Elswick breechloaders in the 1880s used a steel "cup" obturation method. This was quickly superseded in guns designed by the Royal Gun Factory by the French de Bange method, the basic principle of which is still in use today. In British service this became a Crossley pad with an interrupted thread screw block e.g. a Welin screw. The shell was loaded via the breech, followed by the propellant charge in a cloth bag. A single-use "vent sealing tube", a type of primer not dissimilar in appearance to a blank rifle round, was inserted into the breech for firing the gun.
While originally, the term "BL" contrasted with "ML", or "muzzleloader" guns, after muzzleloaders were discontinued, the term came to distinguish between traditional, non-obturating guns with fabric propellant bags and separately loaded shells, and quick-firing QF guns which used self-sealing brass cartridge cases, and which usually had the propellant and projectile fixed together as a unit for faster handling and loading. For instance, Britain before World War I had both QF and BL 6-inch (152 mm) guns. Both were "breech loading" in the general sense, but in the formal nomenclature it separated 6-inch (152 mm) guns with breeches designed for charges in brass cartridge cases for quick-firing QF from those designed for cloth bag charges for breech-loaders BL.
Shells designed for one type were not necessarily suitable for use in the other type; for instance, a BL shell relied upon the tight fit of its driving band in the gun bore to prevent it slipping back when the gun was elevated, but a QF shell could rely upon the cartridge case, either fixed or separate, to prevent it slipping back. This presented difficulties for BL guns at high angles. A special cartridge was developed for BL 9.2-inch (234 mm) guns on HA mountings, with provision for a wooden (beech) stick to be inserted through the centre to prevent the shell slipping back on elevation.
Although fixed ammunition allows for a rapid rate of fire in small to medium guns, BL is a better choice for heavy calibre guns; propellant was loaded in a number of small fabric bags, because a single bag holding the full charge would be far too big and bulky for the handlers to lift. Using fabric allows for the charge to be broken into small, easily handled units, while it would be difficult to design a system by which multiple small metallic-cased charges were loaded and fired at the same time. Using multiple small fabric bags also allows the gunners to use a reduced charge if need be.
Glossary of British ordnance terms
This article explains terms used for the British Armed Forces' ordnance (weapons) and ammunition. The terms may have different meanings depending on their usage in another country's military.
Between decks: applies to a naval gun mounting in which part of the rotating mass is below the deck, and part of it is above the deck. This allows for a lower profile for a turret, meaning that the turrets need not be superfiring (i.e. they can be mounted on the same deck and not obstruct each other at high angles of elevation).
The term BL, in its general sense, stood for breech loading, and contrasted with muzzle loading. The shell was loaded via the breech (i.e. the gunner's end of the barrel, which opened) followed by the propellant charge, and the breech mechanism was closed to seal the chamber.
Breech loading, in its formal British ordnance sense, served to identify the gun as the type of rifled breechloading gun for which the powder charge was loaded in a silk or cloth bag and the breech mechanism was responsible for "obturation" i.e. sealing the chamber to prevent escape of the propellant gases. The term BL was first used to refer to the Armstrong breechloaders, introduced in 1859. Following the discontinuation of Armstrong breechloaders and the period of British rifled muzzle-loaders RML, British breechloaders were re-introduced in 1880. At this point the term rifled breech-loaders RBL was retrospectively introduced to refer to the Armstrong breechloaders, which had a totally different breech mechanism, and since then the term breech-loaders BL has applied exclusively to the type of breechloader introduced from 1880 onwards, using an interrupted-screw breeches.
Early British Elswick breechloaders in the 1880s used a steel "cup" obturation method. This was quickly superseded in guns designed by the Royal Gun Factory by the French de Bange method, the basic principle of which is still in use today. In British service this became a Crossley pad with an interrupted thread screw block e.g. a Welin screw. The shell was loaded via the breech, followed by the propellant charge in a cloth bag. A single-use "vent sealing tube", a type of primer not dissimilar in appearance to a blank rifle round, was inserted into the breech for firing the gun.
While originally, the term "BL" contrasted with "ML", or "muzzleloader" guns, after muzzleloaders were discontinued, the term came to distinguish between traditional, non-obturating guns with fabric propellant bags and separately loaded shells, and quick-firing QF guns which used self-sealing brass cartridge cases, and which usually had the propellant and projectile fixed together as a unit for faster handling and loading. For instance, Britain before World War I had both QF and BL 6-inch (152 mm) guns. Both were "breech loading" in the general sense, but in the formal nomenclature it separated 6-inch (152 mm) guns with breeches designed for charges in brass cartridge cases for quick-firing QF from those designed for cloth bag charges for breech-loaders BL.
Shells designed for one type were not necessarily suitable for use in the other type; for instance, a BL shell relied upon the tight fit of its driving band in the gun bore to prevent it slipping back when the gun was elevated, but a QF shell could rely upon the cartridge case, either fixed or separate, to prevent it slipping back. This presented difficulties for BL guns at high angles. A special cartridge was developed for BL 9.2-inch (234 mm) guns on HA mountings, with provision for a wooden (beech) stick to be inserted through the centre to prevent the shell slipping back on elevation.
Although fixed ammunition allows for a rapid rate of fire in small to medium guns, BL is a better choice for heavy calibre guns; propellant was loaded in a number of small fabric bags, because a single bag holding the full charge would be far too big and bulky for the handlers to lift. Using fabric allows for the charge to be broken into small, easily handled units, while it would be difficult to design a system by which multiple small metallic-cased charges were loaded and fired at the same time. Using multiple small fabric bags also allows the gunners to use a reduced charge if need be.